Re: [syzbot] [bluetooth?] KASAN: slab-use-after-free Read in full_proxy_write

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit:    60c828cf80c0 Merge tag 'for-linus-hexagon-6.14-rc1' of git..
git tree:       upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=147d55f8580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=6e51aa3d0038bbe1
dashboard link: https://syzkaller.appspot.com/bug?extid=422b07c3add2219bc947
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=16decb24580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=133f8eb0580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/409123921db5/disk-60c828cf.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/a0ca4f206436/vmlinux-60c828cf.xz
kernel image: https://storage.googleapis.com/syzbot-assets/643b9310a68b/bzImage-60c828cf.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+422b07c3add2219bc947@xxxxxxxxxxxxxxxxxxxxxxxxx

=====================================================
BUG: KMSAN: uninit-value in full_proxy_write+0x101/0x3f0 fs/debugfs/file.c:394
 full_proxy_write+0x101/0x3f0 fs/debugfs/file.c:394
 vfs_write+0x48a/0x1540 fs/read_write.c:677
 ksys_write+0x240/0x4b0 fs/read_write.c:731
 __do_sys_write fs/read_write.c:742 [inline]
 __se_sys_write fs/read_write.c:739 [inline]
 __x64_sys_write+0x93/0xe0 fs/read_write.c:739
 x64_sys_call+0x3161/0x3c30 arch/x86/include/generated/asm/syscalls_64.h:2
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x1e0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Uninit was stored to memory at:
 __debugfs_file_get+0xe59/0xef0 fs/debugfs/file.c:120
 full_proxy_open_regular+0x67/0xa00 fs/debugfs/file.c:447
 do_dentry_open+0x1bdd/0x26b0 fs/open.c:955
 vfs_open+0x53/0x5b0 fs/open.c:1085
 do_open fs/namei.c:3830 [inline]
 path_openat+0x56a1/0x6250 fs/namei.c:3989
 do_filp_open+0x268/0x600 fs/namei.c:4016
 do_sys_openat2+0x1bf/0x2f0 fs/open.c:1427
 do_sys_open fs/open.c:1442 [inline]
 __do_sys_openat fs/open.c:1458 [inline]
 __se_sys_openat fs/open.c:1453 [inline]
 __x64_sys_openat+0x2a1/0x310 fs/open.c:1453
 x64_sys_call+0x36f5/0x3c30 arch/x86/include/generated/asm/syscalls_64.h:258
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x1e0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Uninit was stored to memory at:
 __debugfs_file_get+0xdff/0xef0 fs/debugfs/file.c:118
 full_proxy_open_regular+0x67/0xa00 fs/debugfs/file.c:447
 do_dentry_open+0x1bdd/0x26b0 fs/open.c:955
 vfs_open+0x53/0x5b0 fs/open.c:1085
 do_open fs/namei.c:3830 [inline]
 path_openat+0x56a1/0x6250 fs/namei.c:3989
 do_filp_open+0x268/0x600 fs/namei.c:4016
 do_sys_openat2+0x1bf/0x2f0 fs/open.c:1427
 do_sys_open fs/open.c:1442 [inline]
 __do_sys_openat fs/open.c:1458 [inline]
 __se_sys_openat fs/open.c:1453 [inline]
 __x64_sys_openat+0x2a1/0x310 fs/open.c:1453
 x64_sys_call+0x36f5/0x3c30 arch/x86/include/generated/asm/syscalls_64.h:258
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x1e0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Uninit was created at:
 slab_post_alloc_hook mm/slub.c:4121 [inline]
 slab_alloc_node mm/slub.c:4164 [inline]
 __kmalloc_cache_noprof+0x8e3/0xdf0 mm/slub.c:4320
 kmalloc_noprof include/linux/slab.h:901 [inline]
 __debugfs_file_get+0x31d/0xef0 fs/debugfs/file.c:101
 full_proxy_open_regular+0x67/0xa00 fs/debugfs/file.c:447
 do_dentry_open+0x1bdd/0x26b0 fs/open.c:955
 vfs_open+0x53/0x5b0 fs/open.c:1085
 do_open fs/namei.c:3830 [inline]
 path_openat+0x56a1/0x6250 fs/namei.c:3989
 do_filp_open+0x268/0x600 fs/namei.c:4016
 do_sys_openat2+0x1bf/0x2f0 fs/open.c:1427
 do_sys_open fs/open.c:1442 [inline]
 __do_sys_openat fs/open.c:1458 [inline]
 __se_sys_openat fs/open.c:1453 [inline]
 __x64_sys_openat+0x2a1/0x310 fs/open.c:1453
 x64_sys_call+0x36f5/0x3c30 arch/x86/include/generated/asm/syscalls_64.h:258
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x1e0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

CPU: 1 UID: 0 PID: 5782 Comm: syz-executor269 Not tainted 6.13.0-syzkaller-09950-g60c828cf80c0 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024
=====================================================


---
If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.